The present invention relates to an oven-stable edible moisture barrier for food products. More particularly, the oven-stable moisture barrier is useful in preventing moisture migration within a multi-component food product between components having different water activities even when the multi-component food product is exposed to elevated temperatures. The oven-stable edible moisture barrier of this invention is formed from a composition comprising an edible, low melting oil having a melting point of about 35xc2x0 C. or lower and an edible, high melting fat having a melting point of about 70xc2x0 C. or higher, wherein the edible, low melting oil and the edible, high melting fat are co-micromilled at a temperature above the melting point of the edible, low melting oil but below the melting point of the edible, high melting fat to form a cream-type mixture. This composition has unique thermal and mechanical properties that makes it ideal as an edible moisture barrier for use in food products, especially for baking applications.
For many food products, moisture levels must be maintained if the product is to exhibit optimum organoleptic properties, quality, and taste. Moisture migration in finished food products can seriously compromise quality, stability, and organoleptic properties. In addition, many chemical and enzymatic deteriorative reactions proceed at rates partially governed by the moisture content of foods. Excessive rates of these reactions can promote deleterious changes in the flavor, color, texture, and nutritive value of food products.
In multi-component food products, particularly those having components with different moisture contents and water activities (e.g., prepackaged cheese and crackers or prepackaged bagel and cheese cream products), moisture can migrate between adjacent components, altering the component""s characteristics and organoleptic properties. In addition to compromising the quality of finished food products, moisture migration can hinder production and distribution of food products. Thus, for example, the cheese in a cheese/cracker product could dry out while, at the same time, the cracker losses its crispness.
One method to prevent moisture migration in foods involves coating one or more surfaces of the food product with an edible moisture barrier. Such barriers should have a low moisture permeability in order to prevent the migration of water between areas of differing water activities. In addition, the barrier should cover the food surface completely, including crevices, and adhere well to the food product surface. The moisture barrier should be sufficiently strong, soft, and flexible to form a continuous surface that will not crack upon handling, yet can be easily penetrated during consumption. In addition, the barrier film""s organoleptic properties of taste, aftertaste, and mouthfeel should be imperceptible so that the consumer is not aware of the barrier when the food product is consumed. Finally, the moisture barrier should be easy to manufacture and easy to use.
Because lipids, such as, for example, oils, fats, and waxes, are composed of lipophilic or water insoluble molecules capable of forming a water impervious structure, they have been investigated for use in moisture barrier films. With respect to oleaginous materials (i.e., fats, oils, sucrose polyesters, and the like) and/or other film forming lipids, it has been shown that, unless an undesirably thick coating is used, the barrier is not effective. Such film forming lipids tend to melt and run under normal baking conditions and, thus, loss film integrity and barrier effectiveness. Wax barriers have disadvantages as moisture barriers because they tend to crack upon handling or with changes in temperatures. Accordingly, many of the barriers in the art use a water-impermeable lipid in association with hydrocolloids or polysaccharides such as alginate, pectin, carrageenan, cellulose derivatives, starch, starch hydrolysates, and/or gelatin to form gel structures or crosslinked semi-rigid matrixes to entrap and/or immobilize the nonaqueous material. In many cases these components are formed as bilayer films. These bilayer films may be precast and applied to a food surface as a self-supporting film with the lipid layer oriented toward the component with highest water activity. See, for example, U.S. Pat. No. 4,671,963 (Jun. 9, 1987), U.S. Pat. No. 4,880,646 (Nov. 14, 1987), U.S. Pat. No. 4,915,971 (Apr. 10, 1990), and U.S. Pat. No. 5,130,151 (Jul. 14, 1992).
There are, however, a number of drawbacks associated with these moisture barriers. The hydrocolloids themselves are hydrophilic and/or water soluble and thus tend to absorb water with time. The absorption of water by the hydrophilic material in moisture barrier is greatly accelerated while the film is directly in contact with foods having a water activity (Aw) above 0.75. The water absorption rate of the hydrophilic material is further accelerated at elevated temperature rendering the barrier ineffective for applications wherein the moisture barrier will be exposed to heat (e.g., baking applications). In addition, some hydrocolloids tend to make the barriers fairly stiff, requiring the addition of a hydrophilic plasticizer (e.g., polyol) to increase flexibility. These plasticizers are often strong moisture binder themselves thus promoting moisture migration into the barriers and decreased structural stability of the barriers. Furthermore, the texture and the required thickness of some of these barriers may make their presence perceptible and objectionable when the product is consumed.
It would be desirable, therefore, to provide an improved edible moisture barrier which retains its effectiveness when exposed to elevated temperatures (i.e., those normally associated with cooking and/or baking). The present invention provides such an oven-stable edible moisture barrier.
The present invention provides an oven-stable edible moisture barrier for food products. This oven-stable moisture barrier is useful in preventing moisture migration within a multi-component food product between components having different water activities and/or moisture contents even when the multi-component food product is exposed to elevated temperatures. The oven-stable edible moisture barrier of this invention is formed from a composition comprising an edible, low melting oil having a melting point of about 35xc2x0 C. or lower, preferably about 15 to about 30xc2x0 C., and an edible, high melting fat having a melting point of about 70xc2x0 C. or higher, wherein the edible, low melting oil and the edible, high melting fat are co-micromilled at a temperature above the melting point of the edible, low melting oil but below the melting point of the edible, high melting fat to form a cream-type mixture. Generally the particle size of the edible, high melting fat is reduced by micromilling to below about 25 microns and preferably in the range of about 1 to about 10 microns. This composition has unique thermal and mechanical properties that makes it ideal as an edible moisture barrier for use in food products, especially for baking applications.
The present invention also provides an edible moisture barrier and a method for preventing moisture migration between food components having different moisture levels. The edible moisture barrier of the invention has a low moisture permeability and is easy to manufacture and use with a variety of food products. The edible moisture barrier of the invention is effective for covering a food surface completely and providing a barrier that is sufficiently strong, soft, and flexible to form a surface that will resist cracking during handling and storage (both at refrigeration and ambient temperatures), but is easily penetrated during consumption, and which can undergo several heating cycles without significant deterioration of, for example, appearance, flavor, rheology, and/or barrier properties. The edible barrier of the invention has organoleptic properties of taste, aftertaste, and mouthfeel that are essentially imperceptible such that the consumer is unaware of the presence of the barrier when the product is consumed. The moisture barrier of the invention is effective for reducing moisture migration between foods at least about 50 percent, and more preferably at least about 90 percent, as compared to food where no moisture barrier is present.
The present invention also provides a method for reducing moisture migration between food components. In this aspect of the invention, the edible moisture barrier is brought into contact with a food component in an amount effective for reducing moisture migration from one food component to another. Generally, the edible moisture barrier is applied to the food component to form an essentially continues barrier layer at least about 10 microns thick, preferably about 20 to about 2000 microns thick, and more preferably about 50 to about 750 microns thick.
The present invention provides an edible moisture barrier composition suitable for forming an edible moisture barrier within a food product having components of differing water activities, said composition comprising an edible, low melting oil having a melting point of about 35xc2x0 C. or less (preferably about 15 to about 30xc2x0 C.) and an edible, high melting fat having a melting point of about 70xc2x0 C. or higher, wherein the edible, low melting oil and the edible, high melting fat are co-micromilled at a temperature above the melting point of the edible, low melting oil but below the melting point of the edible, high melting fat to form a cream-type mixture. Typically, the composition contains about 60 to about 85 percent of the edible, low melting oil and about 15 to about 40 percent of the edible, high melting fat; preferably, the composition contains about 65 to about 75 percent of the edible, low melting oil and about 25 to about 35 percent of the edible, high melting fat.
The present invention also provides an edible moisture barrier between components of differing water activities in a food product, said edible moisture barrier comprising a layer of a composition comprising an edible, low melting oil having a melting point of about 35xc2x0 C. or less (preferably about 15 to about 30xc2x0 C.) and an edible, high melting fat having a melting point of about 70xc2x0 C. or higher, wherein the edible, low melting oil and the edible, high melting fat are co-micromilled at a temperature above the melting point of the edible, low melting oil but below the melting point of the edible, high melting fat to form a cream-type mixture. Generally, the edible moisture barrier is at least about 10 microns thick, preferably about 20 to about 2000 microns thick, and more preferably about 50 to about 750 microns thick.
The present invention also provides a method for preventing moisture migration between a first food component and a second food component having different water activities in a food product, the method comprising:
(1) blending an edible, low melting oil having a melting point of about 15 to about 35xc2x0 C. and an edible, high melting fat having a melting point of about 70xc2x0 C. or higher to form a mixture;
(2) micromilling the mixture at a temperature above the melting point of the edible, low melting oil but below the melting point of the edible, high melting fat to form a cream-type mixture; and
(3) applying the cream-type mixture to at least the first food component to form a layer of the edible moisture barrier effective for preventing moisture migration between the first component and the second food component. Generally, the moisture barrier is at least about 10 microns thick, preferably about 20 to about 2000 microns thick, and more preferably about 50 to about 750 microns thick. Preferably the mixture prior to micromilling is a coarse dispersion with the maximum particle size of the edible, high melting fat being less than about 1000 microns and preferably less than about 500 microns.